1. Field of the Invention
The present invention relates generally to illumination devices and, more particularly, to a signal light assembly for communicating position and orientation of an elongate illumination member and its method of manufacture. In one embodiment, the invention relates specifically to a signal light wand for airport ground personnel to use during all hours of the day or night when assisting in the docking of aircraft.
2. History of the Prior Art
The prior art is replete with light assemblies specifically designed for particular lighting needs and/or specialized applications. Such light assemblies are used for both aesthetic and utilitarian purposes, and include both fixed and portable lighting systems. It is well known to use flood lighting systems for broadly illuminating dark areas, and spot lighting systems for providing select illumination of persons, places, or things in regions that are not otherwise illuminated. A myriad of designs thus fill the prior art repertoire of specialized light assemblies.
Important areas for the application of enhanced lighting systems are found in the transportation industry. Within transportation industry applications, moreover, the single segment reflecting the greatest need for a diversity of specialized lighting systems is the airline industry. Since the use of aircraft is not limited to daylight hours and good weather, aircraft operators depend upon a variety of specialized lighting systems to make night and inclement weather operations possible, safe, and profitable. Such specialized lighting systems are used, for example, to delineate runway thresholds, centerlines, and edges, and to designate taxiways and unsafe areas such as areas under construction which are not otherwise visible under poor ambient light conditions. Additionally, specialized lighting systems illuminate docking terminals, maintenance and servicing areas, and the airplane itself. Specialized lighting assembles are also used by ground crews to guide aircraft to the terminal and otherwise assist the pilot in maneuvering the aircraft on the ground. This function provides one application of the present invention.
Aircraft on the ground are safely guided about the terminal regions of airports through the use of predefined signals between ground crew personnel and the pilots of taxiing aircraft. Taxi lines and docking lines painted on the airport tarmac provide a general reference to the pilot as to where the plane should be turned, and such lines are visible to the pilot even at night when the pilot uses the aircraft's taxi light to illuminate the area in front of the aircraft. Often, however, in the darkness of night and/or bad weather and with the congestion which frequently occurs around the terminal area, only the ground crew personnel are clearly aware of obstacles and/or other parked aircraft which may make the taxi line or docking line an unsafe course for the pilot to follow.
When docking an aircraft, after turning from the taxi line, the pilot brings the nose wheel on to the lead-in, or docking line, and is guided by the ground crew to a specific stopping point on the docking line. From this point at which the aircraft turns from the taxi line onto the docking line and proceeds toward the docking terminal, the pilot relies more and more on the ground crew personnel to provide precise directional and speed guidance. Obstacles must be avoided, and the final position of the nose wheel of the aircraft must be precisely controlled in order to align the aircraft door with the terminal passenger ramp. The pilot generally extinguishes the taxi lights when the aircraft is moved onto the docking line in order to preclude destroying the night vision of the ground crew or the pilots of adjacent aircraft, and because the actual position of the aircraft nosewheel is out of the pilot's direct field of view anyway. During daytime operations, the ground crew directs the pilot in the docking operation by utilizing a pair of elongate signal members, which are generally of a bright color (such as dayglow orange). Similarly, lighted signal wands of various colors are used during nighttime operations. In this manner the pilot is directed to guide the aircraft along the docking line and stop it with the nose wheel positioned at the precise stopping point necessary for alignment of the aircraft doors with the passenger ramp.
As mentioned above, different signalling members are generally used by the ground crew during the daytime from those used during nighttime operations. Conventional nighttime light wands typically include a conventional flashlight unit having a semi-transparent light cone extending over the illumination end thereof for generating an elongate illumination area that is easily visible to the pilot who is taxiing the aircraft. The elongate configuration of the light cone allows select signals to be presented to the pilot based upon the angular orientation and/or movement of the unit by the ground personnel.
The presentation of guidance signals to aircraft by the ground crews is a well established art. Codes have been developed and visual signal sequences may be observed by even the passengers in commercial aircraft as the ground crew personnel move, wave, cross and turn lighted members in direct non-verbal communication with the pilot of an aircraft being taxied. A critical aspect of this illuminated signalling by the ground crew is, of course, the construction of the light surface from which the illumination emanates. The tubular members which are typically used in daylight hours are generally formed of plastic with a readily visible dayglow color. Such bright colors are provided in order to enhance the visibility of signalling to the pilot of the taxiing aircraft. Hollow tubular signalling wands are vibrantly bright, light weight, durable and generally inexpensive. Because of these features they have found widespread acceptance in the air transportation industry. It would be beneficial and cost effective to utilize the same tubular members at all times. However, during periods of darkness or inclement weather, the pilot's ability to see the hollow tubular wands is diminished and signalling by the ground crew must then be enhanced by the above-referenced specialized light assemblies. For this reason, flashlight based signalling units have become essential elements of the ground crew's equipment for use during such periods of darkness.
Conventional flashlights, however, are not as durable as the hollow, plastic daytime wands. One of several problems with such flashlight assemblies is the fragile nature of both the flashlight and the colored light cone. Conventional flashlights have switches, buttons, flanges and the like protruding from what is generally a contoured body. Accidental actuation of the flashlight is possible through inadvertent contact with the protruding switch. Such a switch is also susceptible to unintended actuation if the flashlight is dropped. Additionally, the light cone, which attaches to the lighted end of the flashlight, is typically of a thin-walled construction. Because of these protrusions and the thin-walled construction of the light cone, prior art signal light assemblies often break when they are dropped or subjected to other stresses which are common in the hectic pace of an airport terminal operation.
Enhancement of the reliability, effectiveness, and durability of a signal light assembly in the air transportation industry, and reduction in the number of different types of equipment required by a ground crew, would be greatly beneficial in terms of time and money saved and improved safety. The present invention provides such improvements by utilizing a rugged, translucent tubular member having a surface which is easily recognizable by pilots from a distance, during both daytime and nighttime use. The tubular member has all illumination and activation components disposed therein to comprise both a slightly visible signalling wand for daytime operation and an effective light wand for periods of darkness. No external elements protrude from the right-regular cylindrical body of the subject light assembly to weaken the structural integrity thereof. Its closed-end construction also adds greater strength and durability, and enables it to withstand the rugged treatment of the airport terminal environment. In addition, a recessed switch member provides for more reliable operation of the light wand since with the switch recessed, it is less likely to be accidentally actuated. Likewise the recessed switch does not provide a protuberance which weakens the overall structure. In the preferred embodiment, the construction of the recessed switch seals one end of the tubular housing to prevent moisture intrusion. A versatile and reliable signalling member is thus provided in an elongate construction which is easily recognizable in both daylight and darkness.
It should be noted that the light wand constructed in accordance with the present invention is not restricted to use in the airline industry. Its improvements and benefits are equally applicable to use by highway construction crews, police departments, and other organizations with the need for reliable and effective visual signalling devices.